Cryopumping shield and panel configuration



Feb. 1, 1966 J. G. PIERCE CRYOPUMPING SHIELD AND PANEL CONFIGURATION 2Sheets-Sheet 1 20 Filed Oct. 31, 1962 INVENTOR. JAMES 6. PIERCEATTORNEYS Feb. 1, 1966 J. G. PIERCE 3,232,338

CRYOPUMPING SHIELD AND PANEL CONFIGURATION Filed Oct. 31, 1962 2Sheets-Sheet 2 INVENTOR. JAMES 6. PIERCE ATTORNEYS United States PatentOffice 3,2323% CRYGPUMPHNG AND PANEL CGNFEGURATEQN .iames G. Pierce,Coiumbus, Shin, assignor to Cryovae, Inc, (Johan-thus, (thin, acorporation of Ghio Fiied Oct. 31, 1%2, Ser. No. 216,602 4 Elaims. (4C3.165-67) This invention relates to cryopumping apparatus and moreparticularly to an improved cryopumping shield for use in spacesimulating chambers.

in general, space simulating chambers must simulate, as closely aspossible, the environment in outer space including solar radiationcoal-black space, the pressure of outer space, and other relatedphysical characteristics to which space vehicles are subjected.

Chambers of this general nature include an outer housing structurallyadapted to withstand pressures when evacuated and a cryopumping shieldsuspended within the housing.

The cryopumping shield effects the condensation of gases on surfaceswithin the chamber, the clyopumping being performed by refrigerating theshield with flows of a cryogenic fluid such as gaseous helium.

structurally the shield comprises a wall on the inner surface of whichare mounted a plurality of first panel means that are refrigerated byliquid nitrogen to a temperature approximately 100 degrees Kelvin.

A plurality of second panel means are each mounted to a respective oneof the first panel means between the shield wall and the first panelmeans and are refrigerated to a temperature of approximately degreesKelvin by a gaseous flow from a helium refrigerator.

In accordance with the present invention, the cryopumping shieldcomprises an improved panel means construction that includes a pluralityof upstanding ribs on the side of the panel means that faces the testspecimen. These ribs are so arranged that substantially all of theradiant energy is absorbed by the shield thereby closely to simulate theinfinite heat sink of outer space. Also, this greatly reduces the amountof radiation reflected to the colder panel thereby greatly reducing theamount of refrigeration required to maintain the extreme low temperatureof the panel.

The molecules eminating from the test specimen are defusely reflectedfrom the ribbed panel construction to the colder shielded panel wherebythe entire array pumps efliciently in a manner comparable to an arrayconstructed of flat panels.

It will therefore be understood that the present invention does notincrease cryopumping speed but does materially reduce the amount ofrefrigeration required and greatly enhance the accuracy of simulation ofouter space.

As another aspect of the present invention the novel ribbed panel meansis provided with a conduit for conducting a flow of liquid nitrogenwhereby the panel means is not only cooled by conduction from. therefrigerator wall on which it is mounted but is also directly cooled byits own circulating flow of refrigerant.

As another novel feature the above mentioned second panel means, that iscooled by the flowing helium refrigerant, is mounted to the main panelmeans by a novel spacer and fastener construction formed of plasticmaterial of low thermal conductivity.

It is, therefore, an object of the present invention to provide animproved cryopumpiug shield array provided with a plurality ofupstanding ribs that absorb and difusely reflect molecules emitted fromthe test specimen to a colder shielded panel whereby the entire arraypumps efficiently in a manner comparable to an array constructed ofpanels.

3,232,338 Patented Feb. 1, 1966 It is another object of the presentinvention to provide an improved cryc-pumping shield array that includesrefrigerated panel means provided with conduits that conduct flows ofrefrigerant directly within the panel means.

It is another object of the present invention to provide a cryopumpingshield array that comprises inner and outer panel means detachablyjoined together by mounting members of low thermal conductivity.

Further objects and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanyingdrawings wherein preferred forms of embodiments of the invention areclearly shown.

In the drawings:

FIG. 1 is a broken side sectional view of a space simulating chamberprovided with a cryopumlping shield constructed in accordance with thepresent invention, the section being taken along a vertical planethrough the center line of the chamber;

FIG. 2 is an end sectional view of a panel means construction comprisinga portion of the cryopumping shield of FIG. 1, the section being takenalong a line 22 of FIG. 1;

FIG. 3 is a top sectional view of the space simulating chamber of FIG.1, the section being taken along the line 3-3 of FIG. 1; and

FIG. 4 is an end sectional view of a modified panel means constructed inaccordance with the present invention and comprising a modificationthereof.

Referring in detail to the drawings, FIGS. 1 and 3 illustrate a spacesimulation chamber indicated generally at 1% that comprises an outerhousing 12 and a removable top 16. A vacuum portion, not illustrated,communicates with the interior of housing 12 by means of a conduit 18with the pump having a capacity suflicient to reduce the pressure withinthe housing 12 to approximately 1x10" millimeters of mercury in order toapproximate the pressure of outer space.

A cryopumping shield indicated generally at 20 is supported within thehousing, by suitable mounting means, not illustrated, with the spacesurrounded by shield 20 being in communication with the interior ofhousing 16 via the opening 22. A typical test specimen is disposedwithin the shield and indicated generally at 24.

The cryopumping shield 2th is cooled to a temperature of approximatelydegrees Kelvin by a cooling conduit as which conducts a flow of liquidnitrogen in heat transfer relationship with a wall 28 of the shield.Conduit 26 includes an inlet 34 for the influx of refrigerant which isdischarged at outlet 32.

Referring next to FIGS. 2 and 3 refrigerated wall 28 is provided with aplurality of first panel means indicated generally at 34 and a pluralityof second panel means indicated generally at 36.

Each of the panel means 34 is cooled by conduction as it is welded at ajunction 40 in heat transferring relationship with wall 28.

The outer surface of panel means 34 includes a plurality of upstandingribs 42 that are substantially normal to the plane of the panel means.The outer surfaces of ribs 42 and the inwardly facing surface 44 of thepanel means are finished in flat black to provide the most effectivesurface for absorbing radiant energy.

In the preferred embodiment of FIG. 2 panel means 34 is directly cooledby a conduit portion 46 which is provided with a flow of liquid nitrogenby a suitable supply system, not illustrated.

Each of the shielded panel means 36 includes a conduit portion 48 thatis supplied with a flow of gaseous helium from a suitable heliumrefrigerator in circuit with which conduit 48 is connected.

The colder panel means 36 are mounted in insulated relationship with thewarmer panel means 34 by a plurality of tubular spacers 50 which buttagainst confronting surfaces of the panel means and by a plurality ofpins 52 that extend through holes 54 and 56 through the panel means andwhich include annular spring type retaining washers 58.

The spacers 50 and pins 52 are formed of suitable plastic material oflow thermal conductivity and thereby serve to effectively detachablymount the panel means together in insulated relationship.

Reference is next made to PEG. 4 which illustrates a modified shieldconstruction wherein a modified warmer panel means 34A is mounted to amodified colder panel means 36A.

In this modification the warmer panel means is cooled entirely by heattransfer with the refrigerated wall 28 with the entire inwardly facingsurface 44 being provided with spaced upstanding ribs 42 The shieldedcolder panel means 48 is refrigerated by flowing helium gas in conduit48 with the panel construction differing from that of FIG. 2 by tllocation of the conduit 48 between the mounting pins 52 and tubularspacers 50.

It should be pointed out that the free ends 62 of the warmer panel meansare angled towards refrigerated wall 28 in order to optically shield thecolder panel means from the test specimen.

In operation, molecules of radiant energy from the test specimen 24follow a path such as the one indicated in dotted delineation at 66 inFIG. 3 and upon striking the side of one of the ribs 42 the moleculesare deflected, with the angle of incidence equalizing the angle ofrefraction, against the main body of the warmer panel means as isindicated by the dotted path 68 in FIG. 3.

In other instances the molecules of radiant energy following differentpaths from different points of emission will be reflected againstadjacent ribs 42, on the same panel means, or in some instances againstadjacent ribs or main body portions of adjacent panel means.

It should be pointed out that with warmer panel means 34 provided withflat black inwardly facing surfaces, but without the ribs 42 of thepresent invention, the amount of radiant energy reflected back towardsthe test specimen is in the order of .9 percent, this magnitude ofenergy absorption occurring only once since the path of radiationencounters only one black surface. With the upstanding rib constructionof the present invention, however, 99.1 percent of the energy isabsorbed each time a flat black surface is encountered so it willtherefore be understood that the energy reflected back, when the pathencounters upstanding ribs and hence a multiplicity of flat blacksurfaces, will be the product of .9 percent times .9 percent of .0081percent after two flat black surfaces have been encountered.

While the forms of embodiments of the present invention as hereindisclosed constitute preferred forms, it is to be understood that otherforms might be adopted, all coming within the scope of the claims whichfollow.

I claim:

1. An improved cryopumping shield comprising, in combination, wall meansforming a chamber for containing a test specimen at a test specimenlocation; means for cooling said wall means; and an array of panel meansmounted to said wall means in spaced overlapping relationship with oneanother and in surrounding relationship with said specimen location,each of said panel means comprising an impervious main flange includinga black inner panel surface facing said test specimen location andinclined relative to radial lines from said specimen location wherebyradiant energy from said specimen is reflected to adjacent warmer panelmeans, said panel means including a conduit for a flow of refrigerant.

2. An improved cryopumping shield comprising, in combination, wall meansforming a chamber for containing a test specimen at a test specimenlocation; means for cooling said wall means; an array of warmer panelmeans mounted to said wall means in spaced overlapping relationship withone another and in surrounding relationship with said specimen location,each of said warmer panel means comprising an impervious main flangeincluding a black inner panel surface facing said test specimen locationand inclined relative to radial lines from said specimen locationwhereby radiant energy from said specimen is reflected to adjacentwarmer panel means, said panel means including a conduit for a flow ofrefrigerant; a colder panel means between each of said warmer panelmeans and said wall means, each of said colder panel means including aconduit for a flow of refrigerant; and insulating spacer means mountingsaid colder panel means on said warmer panel means.

3. The apparatus defined in claim 2 wherein said spacer means includes atubular spacer member between said two panel means; and a pin extendingthrough said spacer member and connecting said two panel means, said pinand spacer member being formed of plastic material of low thermalconductivity.

4. An improved cryopumping shield comprising in combination, wall meansforming a chamber for containing a test specimen at a test specimenlocation; means for cooling said wall means; an array of warmer panelmeans mounted to said wall means in spaced overlapping relationship withone another and in surrounding relationship with said specimen location,each of said warmer panel means comprising an impervious main flangeincluding a black inner panel surface facing said test specimen locationand inclined relative to radial lines from said specimen locationwhereby radiant energy from said specimen location is reflected toadjacent warmer panel means; a colder panel means between each of saidwarmer panel means and said wall means, each of said colder panel meansincluding a conduit for flow of refrigerant; and insulating spacer meansmounting said colder panel means on said warmer panel means, said spacermeans including a tubular spacer member between said two panel means;and a pin extending through said spacer member and connecting said twopanel means, said pin and spacer member being formed of plastic materialof low thermal conductivity.

References Cited by the Examiner UNITED STATES PATENTS 2,036,961 4/1936Collier -133 X 2,885,189 5/1959 MacCracken l6546 2,966,780 1/1961 Mills165-133 X 3,130,562 4/1964 Wood et a1. 3,131,396 4/1964 Santeler et al.

OTHER REFERENCES American Vacuum Society, 1959 Vacuum SymposiumTransactions, Pressure Simulation of Outer Space, pp. 129 to 133 by D.J. Santeler, QC 166N3, published in 1959, by Pergomar Press, N.Y.

Space Simulation Chamber, Model 8484, published 9/19/62, by High VacuumEquipment Corp., Hinghan, Mass.

ROBERT A. OLEARY, Primary Examiner.

CHARLES SUKALO, Examiner.

1. AN IMPROVED CRYOPUMPING SHIELD COMPRISING, IN COMBINATION, WALL MEANSFORMING A CHAMBER FOR CONTAINING A TEST SPECIMEN AT A TEST SPECIMENLOCATION; MEANS FOR COOLING SAID WALL MEANS; AND AN ARRAY OF PANEL MEANSMOUNTED TO SAID WALL MEANS IN SPACED OVERLAPPING RELATTIONSHIP WITH ONEANOTHER AND IN SURROUNDING RELATIONSHIP WITH SAID SPECIMEN LOCATION,EACH OF SAID PANEL MEANS COMPRISING AN IMPERVIOUS MAIN FLANGE INCLUDINGA BLACK INNER PANEL SURFACE FACING SAID TEST SPECIMEN LOCATION AND